Apparatus for polarizing a semiconductor wafer and method for fabricating a magnetic semiconductor device

ABSTRACT

The present disclosure provides a method for fabricating a magnetic semiconductor device, including receiving a semiconductor wafer, disposing the semiconductor wafer under a first electromagnetic element, wherein the first electromagnetic element comprises a primary dimension and a secondary dimension from a top view perspective, the primary dimension being greater than the secondary dimension, and displacing the semiconductor wafer along a predetermined path along the secondary dimension of the first electromagnetic element.

BACKGROUND

Magnetic devices are widely used semiconductor devices for electronicapplications, including radios, televisions, cell phones, and personalcomputing devices. One type of well-known magnetic devices is thesemiconductor storage device, such as magnetic random access memories(MRAMs).

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure are best understood from the followingdetailed description when read with the accompanying figures. It isnoted that, in accordance with the standard practice in the industry,various features are not drawn to scale. In fact, the dimensions of thevarious features may be arbitrarily increased or reduced for clarity ofdiscussion.

FIG. 1A is an illustration of a magnetic semiconductor device.

FIG. 1B shows a comparison of resistivity between parallel state andanti-parallel state of a magnetic semiconductor device.

FIG. 2A is a schematic drawing illustrating an apparatus for polarizinga semiconductor wafer, in accordance with some comparative embodimentsof the present disclosure.

FIG. 2B is a schematic drawing illustrating an apparatus for polarizinga semiconductor wafer, in accordance with some comparative embodimentsof the present disclosure.

FIG. 3 shows a flow chart representing method for fabricating a magneticsemiconductor device, in accordance with some embodiments of the presentdisclosure.

FIG. 4 shows a flow chart representing method for fabricating a magneticsemiconductor device, in accordance with some embodiments of the presentdisclosure.

FIG. 5 is a schematic drawing illustrating an apparatus for fabricatinga magnetic semiconductor device, in accordance with some embodiments ofthe present disclosure.

FIG. 6 is a schematic drawing illustrating a cross sectional view of anapparatus for fabricating a magnetic semiconductor device, in accordancewith some embodiments of the present disclosure.

FIG. 7 is a schematic drawing illustrating a top perspective view of anelectromagnet element and a predetermined path of a semiconductor waferduring an operation of polarizing a semiconductor wafer, in accordancewith some embodiments of the present disclosure.

FIG. 8A to 8F are schematic drawings illustrating a top perspective viewof electromagnet elements with various types of shapes, in accordancewith some embodiments of the present disclosure.

FIG. 9 is a schematic drawing illustrating a top perspective view of anelectromagnet element and a predetermined path of a predetermined pathof a semiconductor wafer during an operation of polarizing asemiconductor wafer, in accordance with some embodiments of the presentdisclosure.

FIG. 9A is a schematic drawing illustrating a change of position of anelectromagnet element relative to a position of a semiconductor wafer,in accordance with some embodiments of the present disclosure.

FIG. 10 is a schematic drawing illustrating a top perspective view of anelectromagnet element and a predetermined path of a predetermined pathof a semiconductor wafer during an operation of polarizing asemiconductor wafer, in accordance with some embodiments of the presentdisclosure.

FIG. 10A is a schematic drawing illustrating a change of position of aelectromagnet element relative to a position of a semiconductor wafer,in accordance with some embodiments of the present disclosure.

FIG. 11 is a schematic drawing illustrating a top perspective view of anelectromagnet element and a predetermined path of a semiconductor waferduring an operation of polarizing a semiconductor wafer, in accordancewith some embodiments of the present disclosure.

FIG. 11A is a schematic drawing illustrating a change of position of anelectromagnet element relative to a position of a semiconductor wafer,in accordance with some embodiments of the present disclosure.

FIG. 12A is a schematic drawing illustrating some magnetic lines betweena first electromagnetic element and a second electromagnetic element, inaccordance with some embodiments of the present disclosure.

FIG. 12B and FIG. 12C are schematic diagrams relatively showing amagnetic coverage of an electromagnet element along a primary directionand a secondary direction, in accordance with some embodiments of thepresent disclosure.

FIG. 13 shows a flow chart representing method for fabricating amagnetic semiconductor device, in accordance with some embodiments ofthe present disclosure.

FIG. 14 is a schematic drawing illustrating an operation of die-sawing asemiconductor wafer, in accordance with some embodiments of the presentdisclosure.

DETAILED DESCRIPTION

The following disclosure provides many different embodiments, orexamples, for implementing different features of the provided subjectmatter. Specific examples of components and arrangements are describedbelow to simplify the present disclosure. These are, of course, merelyexamples and are not intended to be limiting. For example, the formationof a first feature over or on a second feature in the description thatfollows may include embodiments in which the first and second featuresare formed in direct contact, and may also include embodiments in whichadditional features may be formed between the first and second features,such that the first and second features may not be in direct contact. Inaddition, the present disclosure may repeat reference numerals and/orletters in the various examples. This repetition is for the purpose ofsimplicity and clarity and does not in itself dictate a relationshipbetween the various embodiments and/or configurations discussed.

Further, spatially relative terms, such as “beneath,” “below,” “lower,”“above,” “upper” and the like, may be used herein for ease ofdescription to describe one element or feature's relationship to anotherelement(s) or feature(s) as illustrated in the figures. The spatiallyrelative terms are intended to encompass different orientations of thedevice in use or operation in addition to the orientation depicted inthe figures. The apparatus may be otherwise oriented (rotated 90 degreesor at other orientations) and the spatially relative descriptors usedherein may likewise be interpreted accordingly.

Notwithstanding that the numerical ranges and parameters setting forththe broad scope of the disclosure are approximations, the numericalvalues set forth in the specific examples are reported as precisely aspossible. Any numerical value, however, inherently contains certainerrors necessarily resulting from the standard deviation found in therespective testing measurements. Also, as used herein, the terms“substantially,” “approximately,” or “about” generally means within avalue or range which can be contemplated by people having ordinary skillin the art. Alternatively, the terms “substantially,” “approximately,”or “about” means within an acceptable standard error of the mean whenconsidered by one of ordinary skill in the art. People having ordinaryskill in the art can understand that the acceptable standard error mayvary according to different technologies. Other than in theoperating/working examples, or unless otherwise expressly specified, allof the numerical ranges, amounts, values and percentages such as thosefor quantities of materials, durations of times, temperatures, operatingconditions, ratios of amounts, and the likes thereof disclosed hereinshould be understood as modified in all instances by the terms“substantially,” “approximately,” or “about.” Accordingly, unlessindicated to the contrary, the numerical parameters set forth in thepresent disclosure and attached claims are approximations that can varyas desired. At the very least, each numerical parameter should at leastbe construed in light of the number of reported significant digits andby applying ordinary rounding techniques. Ranges can be expressed hereinas from one endpoint to another endpoint or between two endpoints. Allranges disclosed herein are inclusive of the endpoints, unless specifiedotherwise.

Referring to FIG. 1A and FIG. 1B, FIG. 1A is an illustration of amagnetic semiconductor device, FIG. 1B shows a comparison of resistivitybetween parallel state and anti-parallel state of a magneticsemiconductor device. Some of the recent development pertinent tomagnetic devices such as MRAMs involves spin electronics, which combinessemiconductor technology and magnetic materials and devices. The spinpolarization of electrons, rather than the charge of the electrons, isused to indicate the state of “1” or “0”. One such spin electronicdevice is a spin torque transfer (STT) magnetic tunneling junction (MTJ)device 1100.

An MRAM device 1100 may include an array of memory cells. In someembodiments, word lines 1102 extend along rows of the memory cells, andbit lines 1101 extend along columns of the memory cells. Each memorycell is located at a cross point of a word line 1102 and a bit line1101. A memory cell stores a bit of information as an orientation of amagnetization. The magnetization orientation of each memory cellindicates one of two stable orientations at any given time. These twostable orientations, parallel and anti-parallel, represent logic valuesof “1” and “0”, as shown in FIG. 1B and will be subsequently discussed.The magnetization orientation of a selected memory cell may be changedby supplying currents to a word line 1102 and a bit line 1101 crossingthe selected memory cell. The currents create two orthogonal magneticfields that, when combined, switch the magnetization orientation of aselected memory cell from parallel to anti-parallel or vice versa.

For example, MTJ device 1100 includes a pinned layer 1111, a tunnellayer 1112, and a free layer 1113. Pinned layer 1111 has a fixedmagnetization direction. The magnetization direction of free layer 1113can be reversed by applying a current through tunnel layer 1112, whichcauses the injected polarized electrons within free layer 1113 to exertso-called spin torques on the magnetization of free layer 1113.

When current flows in the direction from free layer 1113 to pinned layer1111, electrons flow in a reverse direction, that is, from pinned layer1111 to free layer 1113. Thus electrons are polarized to the samemagnetization direction of pinned layer 1111 after passing pinned layer1111, flowing through tunnel layer 1112 and then into and accumulatingin free layer 1113. Eventually, the magnetization of free layer 1113 isparallel to that of pinned layer 1111, and MTJ device 1100 will be at alow resistance state (state of “1” as shown in FIG. 1B). The electroninjection caused by current is referred to as a major injection.

When current flowing from pinned layer 1111 to free layer 1113 isapplied, electrons flow in the direction from free layer 1113 to pinnedlayer 1111. The electrons having the same polarization as themagnetization direction of pinned layer 1111 are able to flow throughtunnel layer 1112 and into pinned layer 1111. Conversely, electrons withpolarization differing from the magnetization of pinned layer 1111 willbe reflected (blocked) by pinned layer 1111 and will accumulate in freelayer 1113. Eventually, magnetization of free layer 1113 becomesanti-parallel to that of pinned layer 1111, and MTJ device 1100 will beat a high resistance state (state of “0” as shown in FIG. 1B). Therespective electron injection caused by current is referred to as aminor injection.

Switching the magnetization orientation of a magnetic semiconductordevice from parallel to anti-parallel or vice versa may be achieved byapplying a magnetic field on the magnetic semiconductor device.Specifically, the magnetic field may be applied over a semiconductorwafer fabricated with a plurality of magnetic semiconductor devices.However, current efficiency of switching the magnetization orientationof magnetic semiconductor devices on a semiconductor wafer isundesirable. A new polarization technique is thus required to enhancethe throughput of magnetic semiconductor devices production and takingother practical factors into consideration, for example, productionpower density and cost.

Referring to FIG. 2A, FIG. 2A is a schematic drawing illustrating anapparatus for polarizing a semiconductor wafer, in accordance with somecomparative embodiments of the present disclosure. An electromagneticelement 11 a may be relatively moved along a path lc along acircumference of a semi-circular path above/under a semiconductor wafer1. However, the interval of polarizing a semiconductor wafer 1 may beundesirably long due to the small scanning area and long scanning path,and the efficiency of polarizing a semiconductor wafer 1 may thus beundesirably lowered.

Referring to FIG. 2B, FIG. 2B is a schematic drawing illustrating anapparatus for polarizing a semiconductor wafer, in accordance with somecomparative embodiments of the present disclosure. An electromagneticelement 11 b may be placed above/under a semiconductor wafer 1 topolarize a semiconductor wafer 1, wherein a size of the magnetic fieldemitting plate 11 b is greater than or close to a size of thesemiconductor wafer 1. Although the efficiency of polarizing asemiconductor wafer 1 may be greater, creating an adequate magnitude ofmagnetic field for polarizing a semiconductor wafer 1 may requireundesirably high power supply, which may induce undesirable higher cost.The cross-sectional area of the electromagnetic element 11 b ispositively related to the required power supply within a given period oftime.

The present disclosure provides an apparatus for polarizing asemiconductor wafer and methods for polarizing the semiconductor waferwith enhanced production throughput and within a reasonable cost,wherein the length of path of relative scanning movement and the costfor providing adequate power supply are reduced by improving theconfiguration of the apparatus for polarizing the semiconductor waferand improving the method for polarizing semiconductor wafer.

Referring to FIG. 3, FIG. 3 shows a flow chart representing method forfabricating a magnetic semiconductor device, in accordance with someembodiments of the present disclosure. The method 100 for fabricating amagnetic semiconductor device includes receiving a semiconductor wafer(operation 103), disposing the semiconductor wafer under a firstelectromagnetic element (operation 106), and displacing thesemiconductor wafer along a predetermined path (operation 109). Detaileddescription of the method 100 is further addressed in FIG. 7, FIG. 10,FIG. 10A, FIG. 11, and FIG. 11A.

Referring to FIG. 4, FIG. 4 shows a flow chart representing method forfabricating a magnetic semiconductor device, in accordance with someembodiments of the present disclosure. The method 200 for fabricating amagnetic semiconductor device includes receiving a semiconductor wafer(operation 203), disposing the semiconductor wafer under a firstelectromagnetic element (operation 206), and displacing thesemiconductor wafer along a first direction parallel to a diameter ofthe semiconductor wafer (operation 209). Detailed description of themethod 200 is further addressed in FIG. 7, FIG. 10, FIG. 10A, FIG. 11,and FIG. 11A.

Referring to FIG. 5 and FIG. 6, FIG. 5 is a schematic drawingillustrating an apparatus for fabricating a magnetic semiconductordevice, FIG. 6 is a schematic drawing illustrating a cross sectionalview of an apparatus for fabricating a magnetic semiconductor device, inaccordance with some embodiments of the present disclosure. Theapparatus 20 for fabricating a magnetic semiconductor device at leastinclude a supporter 25 and an electromagnetic element 21. The apparatus20 may further include an iron core 23, a movable stage 26, a powersupply 27, a coil 24, and/or a temperature detector 28. In some of theembodiments, the electromagnetic element 21 may include a firstelectromagnetic element 21 a and a second electromagnetic element 21 b.

The electromagnetic element 21 is electrically connected to the ironcore 23. The electromagnetic element 21 may or may not have the samematerial with the iron core 23. In some embodiments, the iron core 23has a C-shape, and the first electromagnetic element 21 a is connectedto an end 23 a of the iron core 23, the second electromagnetic element21 b is connected to an opposite end 23 b of the iron core 23. In someembodiments, the first electromagnetic element 21 a is aligned with thesecond electromagnetic element 21 b, that is, the first electromagneticelement 21 a and the second electromagnetic element 21 b may have thesame shape from top view perspective or at respective cross-sectionalview. A gap G is a non-magnetic slit configured on the iron core 23 toseparate two ends of the iron core 23 (or in some embodiments, separatethe first electromagnetic element 21 a and the second electromagneticelement 21 b). Such configuration allows magnetic flux to flow throughthe gap G and its adjacent area from one end to another end. Thesemiconductor wafer 1 can be transferred between the he firstelectromagnetic element 21 a and the second electromagnetic element 21b. After interposing the semiconductor wafer 1 in the gap G, the firstelectromagnetic element 21 a is above the semiconductor wafer 1, whilethe second electromagnetic element 21 b is under the semiconductor wafer1. A distance between the first electromagnetic element 21 a and thesecond electromagnetic element 21 b may be wider than a thickness of thesemiconductor wafer 1 and the supporter 25, but less than a thicknessthat causes the substantial loss of magnitude of magnetic flux. In someembodiments, the gap G is around 15 mm, but the present disclosure isnot limited thereto.

The apparatus 20 may further include a coil 24 wound around a portion,for example, at the end 23 a and the end 23 b, of iron core 23. The coil24 may be made by copper or other suitable conductive materials. Inorder to induce magnetic flux, current is flowed through the coil 24around the iron core 23 to generate magnetic field. Each end of the coil24 is connected to cathode and anode of a power supply 27, and themagnetic flux established by the coil 24 enabling the electromagneticelement 21 to become a polarization means for polarizing magneticsemiconductor devices. In some embodiments, each of the end 23 a and theend 23 b of the iron core 23 is surrounded by a set of coils 24 toenhance the magnetic field at such positions. The coil 24 may or may notpartially surround the electromagnetic element 21. In some of theembodiments, the first electromagnetic element 21 a and the secondelectromagnetic element 21 b is not surrounded by the coils 24. It isnoteworthy that increasing the number of windings of the coil 24 mayincrease the magnitude of the generated magnetic field.

The apparatus 20 may optionally include a temperature detector 28 todetect a temperature of the electromagnetic element 21, the iron core23, and/or the coils 24, so that a temperature of the electromagneticelement 21, the iron core 23, and/or the coils 24 can be controlledwithin a predetermined temperature limitation. For example, atemperature of the electromagnetic element 21, the iron core 23, and/orthe coils 24 is under 70° C. during the operation of polarizing thesemiconductor wafer 1 to avoid safety issue.

Referring to FIG. 5, FIG. 6 and FIG. 7, FIG. 7 is a schematic drawingillustrating a top perspective view of an electromagnet element and apredetermined path of a semiconductor wafer during an operation ofpolarizing a semiconductor wafer, in accordance with some embodiments ofthe present disclosure. In order to efficiently polarize a semiconductorwafer 1, the apparatus 20 further include a movable stage 26 connectedto the supporter 25. The movable stage 26 is configured to displace thesemiconductor wafer 1 disposed on the supporter 25 along a predeterminedpath 90, so the magnetic field between the gap G and an area adjacent togap G can be applied to the semiconductor wafer 1. In some embodiments,in order to efficiently polarize the entire (or at least most of the)semiconductor wafer 1, the movable stage 26 displaces the semiconductorwafer 1 in a scanning manner through the generated magnetic field alongthe predetermined path 90, as the details will be subsequently discussedin FIG. 9 to FIG. 11A. The movable stage 26 may be coupled to acontroller, and such controller may be implemented by software such thatthe methods disclosed herein can be performed automatically orsemi-automatically. For a given computer, the software routines can bestored on a storage device, such as a permanent memory. Alternately, thesoftware routines can be machine executable instructions stored usingany machine readable storage medium, such as a diskette, CD-ROM,magnetic tape, digital video or versatile disk (DVD), laser disk, ROM,flash memory, etc. The series of instructions can be received from aremote storage device, such as a server on a network. The presentinvention can also be implemented in hardware systems, microcontrollerunit (MCU) modules, discrete hardware or firmware.

Referring to FIG. 6, FIG. 7 and FIG. 8A to FIG. 8F, FIG. 8A to FIG. 8Fare schematic drawings illustrating a top perspective view ofelectromagnet elements with various types of shapes, in accordance withsome embodiments of the present disclosure. In some embodiments, inorder to facilitate the scanning efficiency of polarizing thesemiconductor wafer 1 and lowering the requirement of power supply whileprovide adequate magnitude of magnetic flux, the electromagnetic element21 (which may include the first electromagnetic element 21 a and thesecond electromagnetic element 21 b in some embodiments) is configuredto have a linear shape. In the present disclosure, the shape of theelectromagnetic element 21 may be defined in various ways. In someembodiments, a shape of a bottom surface or a top surface of theelectromagnetic element facing the gap G is deemed as the shape of theelectromagnetic element 21. In some other embodiments, theelectromagnetic element 21 has a constant shape along a verticaldirection (which may be in Z direction, as shown in the exampleillustrated in FIG. 6). The shape of the electromagnetic element 21 inany of FIG. 8A to FIG. 8F is a cross-sectional shape along X-Y plane(the X-Y plane is shown in FIG. 5). In some other embodiments, across-sectional shape at the aforesaid position is deemed as the shapeof the electromagnetic element 21. In some other embodiments, the firstelectromagnetic element 21 a and the second electromagnetic element 21 bhave a constant shape along the vertical direction, and the firstelectromagnetic element 21 a and the second electromagnetic element 21 bhave identical and aligned shape from a top view perspective. FIG. 8A toFIG. 8F further provide some embodiments of suitable shapes of anelectromagnetic element 21 of the apparatus 20. For example, a shape ofthe electromagnetic element 21 (or the first electromagnetic element 21a and the second electromagnetic element 21 b) may be quadratic (such asrectangular, rhombus shape, parallelogram shape, trapezoid shape),rounded (such as elliptical), triangular, polygonal, irregular shape, orother suitable shape. It should be noted that the present disclosure isnot limited to the examples illustrated in FIG. 8A to FIG. 8F.Specifically, a shape of the electromagnetic element 21 (or the firstelectromagnetic element 21 a and the second electromagnetic element 21b) may have a primary dimension P and a secondary dimension S from a topview perspective. The primary dimension P is greater than the secondarydimension S. In some embodiments, a direction along the primarydimension P is perpendicular to a direction along the secondarydimension S. In some embodiments, the secondary dimension S is greaterthan 1 mm, so that the coverage of generated magnetic field to the wafermanufactured with magnetic semiconductor devices is large enough and theefficiency of polarizing semiconductor wafer 1 is adequate.

Referring to FIG. 5, FIG. 9 and FIG. 9A, FIG. 9 is a schematic drawingillustrating a top perspective view of an electromagnet element and apredetermined path of a predetermined path of a semiconductor waferduring an operation of polarizing a semiconductor wafer, and FIG. 9A isa schematic drawing illustrating a change of position of a electromagnetelement relative to a position of a semiconductor wafer, in accordancewith some embodiments of the present disclosure. In order to displacethe semiconductor wafer 1 through the magnetic field generated in thegap G, the movable stage 26 displaces the supporter 25 supporting thesemiconductor wafer 1 along a predetermined path through the magneticfield. In some embodiments, as shown in FIG. 9, in order to enhance theefficiency of the operation, the semiconductor wafer 1 is displacedalong a first path 90 p across the electromagnetic element 21 along thesecondary dimension S, which may be parallel to a referential diameterof the semiconductor wafer 1. An edge of the semiconductor wafer 1 moveswith respect to the electromagnetic element 21, and along the first path90 p, any specific location on the wafer 1 is firstly moved toward theelectromagnetic element 21 and then away from the electromagneticelement 21. For the purpose of clear explanation, FIG. 9A illustrateschanging of a position of the electromagnetic element 21 relative to thesemiconductor wafer 1. Herein a distance l_(p) of the first path 90 p isgreater than or equal to a diameter D of the semiconductor wafer 1, sothat the efficiency of polarization can be improved. An entire areabetween an edge to the opposite edge of the semiconductor wafer 1 ispolarized by the generated magnetic field by a displacement along onedirection. Alternatively stated, during the displacement through firstpath 90 p, the physical scanning coverage of electromagnetic element 21at least covers the area from an edge to an opposite edge of thesemiconductor wafer 1 along the first path 90 p. In some embodiments,the entire semiconductor wafer 1 is applied to the magnetic field withinthe displacement along the first path 90 p. However in some otherembodiments, only a portion of the semiconductor wafer 1 is applied tothe magnetic field within the displacement along the first path 90 p.

As of the changing of the position of the electromagnetic element 21relative to the semiconductor wafer 1 illustrated in FIG. 9A, it can bedeemed as the electromagnetic element 21 move along a path 90 p′ acrossthe semiconductor wafer 1, wherein a distance of the path 90 p′ isidentical to the distance l_(p) of the first path 90 p.

Referring to FIG. 10 and FIG. 10A, FIG. 10 is a schematic drawingillustrating a top perspective view of an electromagnet element and apredetermined path of a predetermined path of a semiconductor waferduring an operation of polarizing a semiconductor wafer, and FIG. 10A isa schematic drawing illustrating a change of position of a electromagnetelement relative to a position of a semiconductor wafer, in accordancewith some embodiments of the present disclosure. In the embodiments ofonly a portion of the semiconductor wafer 1 is being polarized by themagnetic field within the displacement along the first path 90 p, themovable stage 26 may further displace the semiconductor wafer 1 along asecond path 90 q and a third path 90 r, wherein the second path 90 q isunparalleled to the first path 90 p (for example, the direction of thesecond path 90 q may be perpendicular to the first path 90 p, which maybe along the direction of the primary dimension P), and the third path90 r is substantially parallel to the first path 90 p (which may bealong the secondary dimension S) while the direction of the third path90 r is opposite to the first path 90 p. In order to ensure that an areabetween the first path 90 p and the third path 90 r is applied to themagnetic field with adequate magnitude of magnetic flux (which will besubsequently discussed in FIG. 12A to FIG. 12C), a distance l_(q) of thesecond path 90 q is less than or equal to the primary dimension P of theelectromagnetic element 21, so that a physical scanning coverage duringthe displacement through the first path 90 p and the third path 90 r areoverlapped, or at least abut with each other. Furthermore, similar topreviously discussed, a distance l_(r) of the third path 90 r is greaterthan or equal to the diameter D of the semiconductor wafer 1, so thatthe physical scanning coverage of electromagnetic element 21 at leastcovers the area from an edge to an opposite edge during the displacementalong the third path 90 r.

As of the changing of the position of the electromagnetic element 21relative to the semiconductor wafer 1 illustrated in FIG. 10A, it can bedeemed as the electromagnetic element 21 move along a path 90 p′ acrossthe semiconductor wafer 1 (which may be along the secondary dimensionS), a path 90 q′ unparalleled to the path 90 p′ (which may beperpendicular to the path 90 p′ or may be along the primary dimensionP), and a path 90 r′ across the semiconductor wafer 1, which is paralleland opposite to the path 90 p′. A distance of the path 90 p′, the path90 q′, and the path 90 r′ are respectively identical to the counterpartthe first path 90 p, the second path 90 q, and the third path 90 r asshown in FIG. 10.

Referring to FIG. 11 and FIG. 11A, FIG. 11 is a schematic drawingillustrating a top perspective view of an electromagnet element and apredetermined path of a predetermined path of a semiconductor waferduring an operation of polarizing a semiconductor wafer, and FIG. 11A isa schematic drawing illustrating a change of position of a electromagnetelement relative to a position of a semiconductor wafer, in accordancewith some embodiments of the present disclosure. In some of theembodiments, after the semiconductor wafer 1 is displaced along thefirst path 90 p, the second path 90 q, and the third path 90 r, aportion of the semiconductor wafer 1 is still not polarized the magneticfield. Thus the movable stage 26 further displaces the semiconductorwafer 1 through a predetermined path so that the remaining not polarizedarea can be polarized by the magnetic field. In some embodiments, thepath includes one or more trajectories, which is similar to a rasterscanning path. For example, subsequent to moving the semiconductor wafer1 along the third path 90 r, the semiconductor wafer 1 may be displacedthrough a fourth path 90 q ₂ along the primary dimension P (which mayhave a same direction as the second path 90 q), a fifth path 90 p ₂along the secondary dimension S (which may have a same direction as thefirst path 90 p), a sixth path 90 q ₃ along the primary dimension P(which may have a same direction as the second path 90 q), and/or aseventh path 90 r ₂ along the primary dimension P (which may have a samedirection as the third path 90 r), or further include subsequent paths,until a predetermined area of the semiconductor wafer 1 are polarized bymagnetic field. In some embodiments, the first path 90 p, the secondpath 90 q, the third path 90 r, the fourth path 90 q ₂, the fifth path90 p ₂, the sixth path 90 q ₃, the seventh path 90 r ₂, or subsequentpaths are linear so that the efficiency of polarizing the semiconductorwafer 1 is improved. Furthermore, a distance l_(p2) of fifth path 90 p ₂and/or a distance l_(r2) of seventh path 90 r ₂ is greater than or equalto a diameter D of the semiconductor wafer 1, while a distance l_(q2) ofthe fourth path 90 q ₂ and/or a distance l_(q3) of the sixth path 90 q ₃is less than or equal to the primary dimension P of the electromagneticelement 21, so that a physical scanning coverage during the displacementthrough the third path 90 r, the fifth path 90 p ₂, and/or the seventhpath 90 r ₂ are overlapped, or at least abut with each other.

As of the changing of the position of the electromagnetic element 21relative to the semiconductor wafer 1 illustrated in FIG. 11A, it can bedeemed as the electromagnetic element 21 move along a path 90 p′ acrossthe semiconductor wafer 1 (which may be along the secondary dimensionS), a path 90 q′ unparalleled to the path 90 p′ (which may be along theprimary dimension P), a path 90 r′ across the semiconductor wafer 1(which is parallel and opposite to the path 90 p′), a path 90 q ₂′unparalleled to the path 90 p′ (which may be along the primary dimensionP), a path 90 p ₂′ across the semiconductor wafer 1 (which may be alongthe secondary dimension S), a path 90 q ₃′ unparalleled to the path 90 p₂′ (which may be along the primary dimension P), a path 90 r ₂′ acrossthe semiconductor wafer 1 (which is parallel and opposite to the path 90p ₂′).

Referring to FIG. 12A, FIG. 12B, and FIG. 12C, FIG. 12A is a schematicdrawing illustrating several magnetic lines between a firstelectromagnetic element and a second electromagnetic element, FIG. 12Band FIG. 12C are schematic diagrams relatively showing a magneticcoverage of a electromagnet element along a primary direction and asecondary direction, in accordance with some embodiments of the presentdisclosure. Due to the fringing effect induced around the gap G and/orthe curl of magnetic flux 21 m of the magnetic field, a magneticcoverage of the generated magnetic field on the semiconductor wafer 1 isgreater than the cross-sectional area along x-y plane of theelectromagnetic element 21, as shown in FIG. 5. In order to effectivelypolarize a semiconductor wafer 1 with desired reliability, in someembodiments, a magnitude of the magnetic field generated by theelectromagnetic element 21 has to be greater than a predeterminedthreshold value, for example, 1.8 Tesla. Thus a magnetic coverage of themagnetic field generated by the electromagnetic element 21 may bedefined as a coverage area passed by a magnetic flux of the magneticfield with a magnitude greater than the predetermined threshold value.For example, in order to polarize a given semiconductor wafer 1 withadequate reliability, the magnitude of the magnetic field passingthrough the semiconductor wafer 1 may be at least greater than 1.8Tesla. In some embodiments, a primary dimension P of each of the firstelectromagnetic element 21 a and the second electromagnetic element 21 bis about 40 mm, and a secondary dimension S of each of the firstelectromagnetic element 21 a and the second electromagnetic element 21 bis about 4 mm, and a gap between the first electromagnetic element 21 aand the second electromagnetic element 21 b is about 5 mm. In thisexample, a magnetic coverage of the magnetic field generated by thefirst electromagnetic element 21 a and the second electromagneticelement 21 b has a width of about 65 mm along the primary dimension Pand a width of about 20 mm along the secondary dimension S. That is, themagnetic coverage of the electromagnetic element on the semiconductorwafer 1 is greater than a physical cross sectional area of the firstelectromagnetic element 21 a or the second electromagnetic element 21 b.

Due to the aforesaid phenomena, the magnetic coverage of theelectromagnetic element during displacing the semiconductor wafer 1along the first path 90 p (as shown in FIG. 11) may overlap with themagnetic coverage of the electromagnetic element during displacing thesemiconductor wafer 1 along the third path 90 r, and the magneticcoverage during displacing along the fifth path 90 p ₂ may overlap withthe magnetic coverage of the magnetic field during displacing thesemiconductor wafer 1 along the third path 90 r. Alternatively stated,the magnetic coverage on the semiconductor wafer 1 during a path alongthe secondary dimension S overlaps with the magnetic coverage on thesemiconductor wafer 1 during a subsequent/previous path along thesecondary dimension S. By this configuration, some of the area can betreated by the magnetic field with a magnitude greater than thepredetermined threshold value by more than one time, thus not only thepolarization efficiency but also the yield of switching the magneticsemiconductor device on the semiconductor wafer 1 from parallel state toanti-parallel state (or vice versa) can be improved.

Referring to FIG. 13, FIG. 13 shows a flow chart representing method forfabricating a magnetic semiconductor device, in accordance with someembodiments of the present disclosure. The method 300 for fabricating amagnetic semiconductor device includes receiving a semiconductor wafer(operation 303), disposing the semiconductor wafer under a firstelectromagnetic element (operation 306), displacing the semiconductorwafer along a predetermined path (operation 307), and die-sawing thesemiconductor wafer (operation 309).

Referring to FIG. 14, FIG. 14 is a schematic drawing illustrating anoperation of die-sawing a semiconductor wafer, in accordance with someembodiments of the present disclosure. After the magnetic semiconductordevices on the semiconductor wafer 1 are polarized, the semiconductorwafer 1 is singulated into individual semiconductor dies. In someembodiments, a die-sawing operation is performed on the semiconductorwafer 1 by sawing through predetermined scribe line 99. Since theoperation of switching the magnetic semiconductor device on thesemiconductor wafer 1 from parallel state to anti-parallel state (orvice versa) is performed beforehand, the semiconductor wafer 1 can besingulated by die-sawing and then packaged, thus facilitate the yieldand the efficiency of polarization since it may take less time topolarize the semiconductor wafer 1 comparing to polarize the singulated,individual device packages.

The methods provided in the present disclosure can be applied to varioustypes of magnetic semiconductor devices, such as MRAM or other types ofmemory devices, or the like. Some of the methods provided in the presentdisclosure can be applied to technology nodes under N40, such as N40,N28, N20, N16, et cetera.

The present disclosure provides an apparatus for polarizing asemiconductor wafer, a method for fabricating a magnetic semiconductordevice, and a method for fabricating a magnetic semiconductor device.The electromagnetic element 21 of the apparatus 20 has a linear shape,that is, having a primary dimension P greater than a secondary dimensionS. The configuration of the electromagnetic element 21 can generateadequate magnitude of magnetic field while lower power consumption.Furthermore, by displacing the semiconductor wafer 1 along apredetermined linear path through the magnetic field generated by theelectromagnetic element 21, the efficiency of polarizing thesemiconductor wafer 1 is improved. Specifically, the displacement pathmay include a first path along the secondary dimension across theelectromagnetic element 21, and optionally a second path perpendicularto the first path and a third path parallel and opposite to the firstpath. Such combination of the displacement path of the semiconductorwafer 1 and the shape of the electromagnetic element 21 reduces theinterval of scanning through the semiconductor wafer 1 and thus improveefficiency of fabrication. In some embodiments, distances between thepaths along the secondary dimension may be less than or equal to theprimary dimension of the electromagnetic element 21, so that thephysical coverage of the electromagnetic element 21 and/or a magneticcoverage of the electromagnetic element 21 can be overlapped during suchpaths, so some area of the semiconductor wafer 1 can be treated by themagnetic field more than one time, thence the reliability ofpolarization can be enhanced.

Some embodiments of the present disclosure provide a method forfabricating a magnetic semiconductor device, including receiving asemiconductor wafer, disposing the semiconductor wafer under a firstelectromagnetic element, wherein the first electromagnetic elementcomprises a primary dimension and a secondary dimension from a top viewperspective, the primary dimension being greater than the secondarydimension, and displacing the semiconductor wafer along a predeterminedpath along the secondary dimension of the first electromagnetic element.

Some embodiments of the present disclosure provide a method forpolarizing a magnetic semiconductor device, including receiving asemiconductor wafer having the magnetic semiconductor device, disposingthe semiconductor wafer under an electromagnetic element, theelectromagnetic element having a primary dimension and a secondarydimension shorter than the primary dimension, displacing thesemiconductor wafer along a first direction parallel to a diameter ofthe semiconductor wafer, and die-sawing the semiconductor wafer.

Some embodiments of the present disclosure provide an apparatus forpolarizing a semiconductor wafer, including a supporter configured tosupport the semiconductor wafer, an electromagnetic element overlappingwith the supporter, the electromagnetic element comprising a primarydimension and a secondary dimension from a top view perspective, theprimary dimension being greater than the secondary dimension, and apower supply connected to the electromagnetic element.

The foregoing outlines features of several embodiments so that thoseskilled in the art may better understand the aspects of the presentdisclosure. Those skilled in the art should appreciate that they mayreadily use the present disclosure as a basis for designing or modifyingother operations and structures for carrying out the same purposesand/or achieving the same advantages of the embodiments introducedherein. Those skilled in the art should also realize that suchequivalent constructions do not depart from the spirit and scope of thepresent disclosure, and that they may make various changes,substitutions, and alterations herein without departing from the spiritand scope of the present disclosure.

Moreover, the scope of the present application is not intended to belimited to the particular embodiments of the process, machine,manufacture, composition of matter, means, methods and steps describedin the specification. As one of ordinary skill in the art will readilyappreciate from the disclosure of the present invention, processes,machines, manufacture, compositions of matter, means, methods, or steps,presently existing or later to be developed, that perform substantiallythe same function or achieve substantially the same result as thecorresponding embodiments described herein may be utilized according tothe present invention. Accordingly, the appended claims are intended toinclude within their scope such processes, machines, manufacture,compositions of matter, means, methods, or steps.

What is claimed:
 1. A method for fabricating a magnetic semiconductordevice, comprising: receiving a semiconductor wafer comprising aplurality of magnetic device, the plurality of magnetic device have afirst resistance state; and changing a resistance state of the pluralityof magnetic device from the first resistance state to a secondresistance state different from the first resistance state, comprising:disposing the semiconductor wafer under a first electromagnetic element,wherein the first electromagnetic element comprises a primary dimensionand a secondary dimension from a top view perspective, the primarydimension being greater than the secondary dimension; and displacing thesemiconductor wafer along a predetermined path along the secondarydimension of the first electromagnetic element.
 2. The method of claim1, further comprising performing a die-sawing operation to thesemiconductor wafer after displacing the semiconductor wafer.
 3. Themethod of claim 1, further comprising disposing the semiconductor waferabove a second electromagnet element.
 4. The method of claim 3, whereinthe first electromagnetic element aligns with the second electromagnetelement.
 5. The method of claim 1, further comprising displacing thesemiconductor wafer along the primary dimension subsequent to displacingthe semiconductor wafer along the secondary dimension.
 6. The method ofclaim 5, wherein the semiconductor wafer is displaced along the primarydimension by a distance smaller than or equal to the primary dimension.7. A method for fabricating a magnetic semiconductor device, comprising:receiving a semiconductor wafer comprising a plurality of magneticsemiconductor device having a first resistance state; changing aresistance state of the plurality of magnetic device from the firstresistance state to a second resistance state different from the firstresistance state, comprising: disposing the semiconductor wafer under anelectromagnetic element, the electromagnetic element having a primarydimension and a secondary dimension shorter than the primary dimension;and displacing the semiconductor wafer along a first direction parallelto a diameter of the semiconductor wafer; and die-sawing thesemiconductor wafer.
 8. The method of claim 7, further comprisingdisplacing the semiconductor wafer along the first direction by a firstdistance, the first distance being equal to or greater than the diameterof the semiconductor wafer.
 9. The method of claim 8, further comprisingdisplacing the semiconductor wafer along a second directionperpendicular to the first direction.
 10. The method of claim 9, furthercomprising displacing the semiconductor wafer along the second directionby a second distance, the second distance being smaller than or equal tothe primary dimension of the electromagnetic element.
 11. The method ofclaim 9, further comprising displacing the semiconductor wafer along athird direction subsequent to displacing the semiconductor wafer alongthe second direction, wherein the third direction is opposite to thefirst direction.
 12. The method of claim 7, wherein die-sawing thesemiconductor wafer is performed subsequent to changing the resistancestate of the plurality of magnetic device.
 13. The method of claim 7,wherein displacing the semiconductor wafer along the first directioncomprises transferring the semiconductor wafer so that an edge of thesemiconductor wafer moves with respect to the electromagnetic element.14. A method for fabricating a magnetic semiconductor device,comprising: forming a magnetic device on a wafer; and changing aresistance state of the magnetic device from a first state to a secondstate different from the first state, comprising: placing the wafer on amovable stage; and displacing the wafer from a first position to asecond position different from the first position along a firstdirection, wherein a third position between the first position and thesecond position is directly under a first electromagnetic element, andthe first electromagnetic element has a primary dimension greater than asecondary dimension.
 15. The method of claim 14, wherein a distancebetween the first position and the second position is greater than adiameter of the wafer.
 16. The method of claim 14, further comprisingdie-sawing the wafer after displacing the wafer from the first positionto the second position.
 17. The method of claim 14, displacing the waferfrom the first position to the second position further comprises:displacing the wafer above a second electromagnetic element under thethird position.
 18. The method of claim 14, wherein when the wafer is atthe first position or the second position, the wafer is free from beingunder a coverage of a vertical projection of the first electromagneticelement.
 19. The method of claim 14, further comprising detecting atemperature of the first electromagnetic element, and cooling down thefirst electromagnetic element when the temperature is greater than athreshold temperature.
 20. The method of claim 14, further comprisingdisplacing the wafer along a second direction opposite to the firstdirection.